Humanity... so disappointing!

I am just blown away every time someone I trust lets me down or lies to me... and I don't know why. We're all human, just human. We all fail on occasion, even those of us who try our best not to. We all let the people we love down at one point or another. We can't help it, we're just not perfect, and no matter how determined we are to be Christ-like, we're still gonna fail from time to time. Because I know this, and because I have come a long way with learning to be forgiving because God has forgiven me and instructs us to do the same, I can overlook these occasions when my friends and family hurt me in some way because of their humanity. What I have a much harder time overlooking is when someone continuously lies to me or hurts me somehow, and even worse... when they don't admit it. This is so hard to deal with! It's detrimental to any kind of a relationship! What do you do about it? Do you continue to forgive the person? Yes, I believe we should, and I do. Do we continue the relationship with that person though? This is the hard part for me. Obviously if the person is family, ending the relationship is probably not an option (unless of course the situation is physically abusive). But what if it's a friend, boyfriend, fiance, or coworker? Do you continue to allow this person to be a large part of your life, to spend time with them that you don't absolutely have to? I don't know. At what point is enough enough? At what point do you tell them that they have crossed the line with you? Do you tell them at all? Do you keep it to yourself and slowly ease your way out of the relationship? I know some people would opt for this last option, perhaps because they don't like confrontation, but that's just not me. Now I'm not one that enjoys an uncomfortable confrontation either (although I will admit that I used to be one of those brash people that didn't mind it at all... but I've grown up since then), but I'm not afraid of them either. I tend to feel that to avoid confronting the person about it would be somewhat shady, or even downright dishonest and unfair to that person. Don't they deserve to know how you are feeling? I mean, if you're truly friends and/or you love each other, shouldn't you be able to talk about any relationship problem or hurt that has developed between you? I would hope so. At what point do you do this though, and should it include (for lack of a better, less dominating term) an ultimatum? I hate relationship ultimatums, but are they necessary in some instances? Are we as Christians called to continue to let someone hurt us, even if it's just on an emotional level? I'm torn, I'm hurt, and I'm just gonna have to pray about it...